From: Pavel Skripkin paskripkin@gmail.com
stable inclusion from stable-v5.10.46 commit 5946fbf48355f5a8caeff72580c7658da5966b86 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4HY CVE: CVE-2021-47249
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
[ Upstream commit 49bfcbfd989a8f1f23e705759a6bb099de2cff9f ]
Syzbot reported memory leak in rds. The problem was in unputted refcount in case of error.
int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size, int msg_flags) { ...
if (!rds_next_incoming(rs, &inc)) { ... }
After this "if" inc refcount incremented and
if (rds_cmsg_recv(inc, msg, rs)) { ret = -EFAULT; goto out; } ... out: return ret; }
in case of rds_cmsg_recv() fail the refcount won't be decremented. And it's easy to see from ftrace log, that rds_inc_addref() don't have rds_inc_put() pair in rds_recvmsg() after rds_cmsg_recv()
1) | rds_recvmsg() { 1) 3.721 us | rds_inc_addref(); 1) 3.853 us | rds_message_inc_copy_to_user(); 1) + 10.395 us | rds_cmsg_recv(); 1) + 34.260 us | }
Fixes: bdbe6fbc6a2f ("RDS: recv.c") Reported-and-tested-by: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Reviewed-by: Håkon Bugge haakon.bugge@oracle.com Acked-by: Santosh Shilimkar santosh.shilimkar@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Chen Jun chenjun102@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Zheng Zucheng zhengzucheng@huawei.com --- net/rds/recv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/rds/recv.c b/net/rds/recv.c index 3ca278988b52..ccf0bf283002 100644 --- a/net/rds/recv.c +++ b/net/rds/recv.c @@ -705,7 +705,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
if (rds_cmsg_recv(inc, msg, rs)) { ret = -EFAULT; - goto out; + break; } rds_recvmsg_zcookie(rs, msg);